No. 155, July 1996
Most everyone knows that irrigated potato acreage has been expanding in North Dakota, but did you know it is also expanding regionally? Irrigated potato production has increased significantly in southern Manitoba, northwestern Minnesota and Saskatchewan during the last 6 years. The growth of irrigated potatoes in North Dakota (figure 1) mirrors what has been happening regionally. The number of irrigated potato acres will probably continue to increase in the region for a few more years.
Figure 1.Irrigated potato acres in North Dakota
(ASCS reported acres).
Tom Scherer, (701) 231-7239
Extension Agricultural Engineer
Water Spouts: www.ext.nodak.edu/extnews/snouts/
We have seen an increase in high value crops research in North Dakota over the last few years. Following is a quick rundown of projects underway and being planned.
Dr. Richard Greenland at the Oakes Irrigation Field Trials has been gearing up for vegetable research at the station, which is run by the Garrison Conservancy District. Greenland has the following plots for 1996:
Dr. Dean Steele is combining irrigation research with Dr. Chiwon Lee at the Absaraka horticultural site for 1996. He is using carrot plots to study three alternatives. One will be non-irrigated while the other two will be drip irrigated. The two drip irrigated plots will demonstrate above ground and underground irrigation. The irrigated plots are being monitored remotely by recording tensiometer readings and relaying them back to computers on the NDSU campus.
Lee is also studying fertility at the Absaraka carrot site under drip irrigation along with seed starting efficiency under sprinkler irrigation. He will be looking at the various nutrient levels for effect on the sugar content, taste and other quality characteristics of the variety Bolero.
North Central North Dakota is receiving some exposure to vegetable plots this year for the first time. Terry Gregoire, NDSU Extension Agronomist has planted onions, carrots and cabbage. The cooperation of a Cando irrigator has made this new project possible. They are looking at the following areas of interest:
Jim Weigel, Area Extension Specialist in Irrigation, is working with the Turtle Lake Irrigation District and a farmer cooperator to evaluate vegetable production in the Turtle Lake area. This is also a first-time effort. Carrots, cabbage and onions were planted in the study plot to look at the following points:
Dr. Chiwon Lee, Professor of Horticulture at NDSU, has the following studies in place for vegetable production:
Rudy Radke, (701) 845-8528
Area Ag Diversification Specialist
NDSU Extension Service
North Dakota is classified as cow/calf state, with most cattle production associated with cow/calf pairs. Historically, when grass quits growing in the fall, calves are weaned in October and November, sold at the auction barn, and shipped to the central region of the United States where they are backgrounded, finished, and sent to slaughter. The new philosophy (whether it is new or not is questionable) today is to try to take advantage of our excess forages and grains and feed it to our calves in North Dakota. We can keep some of the money in the state by backgrounding and finishing these cattle in feedlots, rather than shipping them south. When and if the new slaughter plant or plants are built in North Dakota, some of these animals will have a final outlet within the state. In other words, try to keep as much of the incomes and expenses in North Dakota, keep the money in our economy, and achieve the added value in our state rather then somewhere else.
As these feedlots become established, a surrounding feed base may need to be developed. Whether you're backgrounding or finishing, feeding these animals will include some silage and grain. To maximize your return, in terms of tonnage or grain per acre, irrigation may and will play a role surrounding these feedlots. Many irrigation pivots are also found associated with high value crops (potatoes, beets, carrots, beans, and peas) which need to be incorporated with other crops such as corn, small grains, sorghums, and alfalfa in the rotation. These other crops can become important feed types used in the feedlot industry.
When developing a cropping system that will include incorporating feed grains and forages in your irrigation planning, knowing what types of feeds are desirable is important. Remember, in the feedlot setting, silage and grains will be the dominate feed types. Tthe most common silage crop used will be corn. Corn gives a very high tonnage forage that is high in energy. Other crops that can be ensiled successfully and are used frequently are forage sorghums, sorghum-sudangrass, pearl millet, and alfalfa. Barley and oats also provide a very good haylage type crop. All are annual plants with the exception of alfalfa, which is a perennial.
Corn is the most common plant used for many reasons. One overpowering reason is the flexibility of using corn as a forage as well as harvesting it for grain. Corn also provides a desirable grain for feeding and finishing livestock. A person can plant corn with the purpose of ensiling, but if corn grain prices rise (such as in 1996), you can harvest for grain and sell it outside your feedlot, grazing animals on the corn stalks. If corn prices remain low, you can decide the most economic use of the crop for grain or silage and feed within your feedlot as planned.
Often, when planning feedstuffs for your feedlot, planting barley and corn for feed grains will be desirable and planting a silage type crop (corn, sorghum, millet) will also be needed. Alfalfa becomes a good crop when you need to put a field in some type of permanent or temporary crop for two to four years. Irrigated alfalfa will give a high tonnage crop that is high in protein. However, you will still need to provide grain for energy.
So what are the pros to irrigating versus dryland silage and grain production? Irrigating obviously increases tonnage and reassures the highest possible grain production barring any uncontrollable weather events. For example, corn silage production in North Dakota averaged 6.5 tons per acre on dryland acres compared to 14.9 tons per acre on irrigated acres in 1995, according to the North Dakota Agricultural Statistics Service (1996). Irrigating corn in 1995 created an average 2.3 times increase in forage production compared to dryland. In 1994, irrigating corn created an average 2.8 times increase in forage production compared to dryland.
In terms of corn grain production, irrigating provided a 1.3 times increase in 1994 and 1995 compared to dryland. The added increase in forage and grain production on irrigated acres compared to dryland is directly related to precipitation patterns. If rainfall moisture is short, irrigation will provided a dramatic increase in production; however, when moisture conditions are above average during the growing period, increases will be less noticeable.
Table 1. Mean corn silage and grain production on dryland and irrigated lands in North Dakota in 1994 and 1995. -------------------------------------------------- Silage (tons/ac) Grain (bu/ac) Year Dryland Irrigated Dryland Irrigated -------------------------------------------------- 1994 6.1 17.0 97.2 122.9 1995 6.5 14.9 76.2 101.4 --------------------------------------------------
As feedlot numbers increase in North Dakota, land managers associated with the lots should consider the benefits of irrigation in terms of increased forage and grain production, especially if acres are limited for the feed base. Working closely with area farmers using irrigation could be very beneficial. High value crops need to be in a desired rotation with other crops. These crops can include forages and grains used for feed in the lot.
Kevin K. Sedivec, (701) 231-7647
Extension Rangeland Specialist
Corn borer emergence is under way in North Dakota. Moth activity is relatively light, but it is time to begin monitoring for them.
Managing corn borer in North Dakota is a challenge due to the lengthy emergence interval of the moths from overwintering. In North Dakota, borers have the potential for one or two generations during the season. The two generation type borers are present in the southeast quarter of the state. They have begun to emerge and represent the first flush of larval feeding. The single generation borer is present throughout North Dakota, emerging from late June and beyond.
The challenge of the crop manager is to distinguish when egg laying and larval populations can be tolerated or they need to be controlled. Corn should be monitored weekly for at least five weeks once plants exceed an extended leaf height of 17 inches. At this point, corn borer larvae will be able to survive on the plant. Inspect plants for the presence of egg masses, whorl feeding, and active larvae. Observing moth activity around field margins or within the field may alert you to developing infestations.
Over the past two seasons corn borer have reached levels requiring treatment during the second and third weeks of July. There are no early indications to suggest we will experience anything different this year.
Whorl stage corn -- Pull the whorls from 10 plants at 5 locations across the field. Select whorls at random, avoiding damaged plants. Unwrap the whorl leaves; count and record the number of live larvae found.
Older treatment thresholds based strictly on percent damage suggest that irrigated corn should be treated when 35% of the plants show damage in the whorl. For maximum borer control, treatment should be applied when most of the infested plants have eggs in the black head stage (borers are about to hatch) or show evidence of early shotholing. Treatments applied after most borers have begun tunneling into plants will be ineffective.
Center Pivot Application (Chemigation) -- The products Ambush 2E or 25W, Asana XL, Dipel ES, Sevin, Lorsban 4E, Penncap-M, Pounce 3.2E or 25W, and Warrior are labelled for center pivot application. You must be sure your system is properly equipped and calibrated before attempting this procedure. Equipment designed to prevent back siphoning into the well is absolutely essential.
Use the following worksheet to help make decisions about the profitability of treating an individual field. ---------------------------------------------------------------------------------------------- Worksheet for corn borer in whorl stage corn . . . you fill in the blanks ---------------------------------------------------------------------------------------------- 1. ______ % of plants infested x ______ Avg no. borers/plant = ______ Borers per plant 2. ______ borers per plant x ______ % yield loss per borer* = ______ percent yield loss 3. ______ percent yield loss x ______ expected yield (bu/acre) = ______ bushels/a loss 4. ______ bushel loss per acre x ______ price per bushel =$ ______ loss per acre 5. ______ loss per acre x ______ percent control** =$ ______ preventable loss/a 6. ______ preventable loss/acre - ______ cost of control per acre =$ ______ profit (loss)/acre ---------------------------------------------------------------------------------------------- * 5% for corn in the early whorl stage; 4% for late whorl; 6% for pretassel ** 80% for granules; 50% for sprays.
Phillip Glogoza, (701) 231-7581
Chemigation is the addition of any chemical to the water used for irrigation. In the past, this practice has been called fertigation for adding fertilizer, herbigation when herbicides were added, fungigation for fungicides, etc. Now it is just called chemigation.
Chemigation is a very efficient and effective irrigation management tool when used properly. In fact it is recognized as a best management practice for irrigated agriculture. When chemigation is used with an irrigation system, the irrigation water delivery system and the chemical injection equipment must conform to state laws regarding backflow prevention. In addition, when pesticides are added to irrigation water, the pesticide label must state that it can be used for chemigation and be applied through center pivot irrigation systems.
Center pivot systems are used on nearly 75% of the irrigated land in North Dakota. With the cost of pesticides increasing every year, it makes a lot of sense to properly calibrate a center pivot irrigation system for chemigation. Below are five easy steps to follow to ensure that a center pivot chemigation system is properly calibrated.
1. Calibrate the injector pump.
Determine the injection rate of the chemical injection pump for a particular setting of the injection rate control knob. This must be done with the irrigation system running so the injection pump is working against the water pipeline pressure. Do this by letting the injection pump draw from a calibrated container on the suction side of the pump. Determine the time in minutes to pump 1 gallon of liquid, then use this equation to determine the injection pump rate in gallons per hour:
Injector Pump Rate (gal/hr) = (60) / (minutes to pump 1 gallon)
2. Determine the number of hours it will take to make one complete revolution around the field at the speed the center pivot will be operated and the total number of acres the pivot covers:
Time for one complete revolution = hours
Total area the center pivot covers = acres
3. Determine the total gallons to be injected.
Multiply the injection pump rate (step 1) by the total hours to cover the field (step 2). Use the following equation:
Total Gallons Injected = (gal/hr) x (hours to cover field)
4. Determine the amount of chemical required to cover the field.
Multiply the field acreage by the chemical rate as specified for the particular chemical and crop. For nitrogen it would be the pounds N per acre and for pesticides it would be the rate that is recommended
on the label for the particular crop. Use the following equation:
Total Chemical Volume = field acres (step 2) x (chemical volume/acre)
5. Add the total chemical (step 4) to the injection supply tank and then add water to the supply tank until you have the necessary total volume to be injected (step 3).
When working with many pesticides and dry chemicals, make sure you have a method to agitate the injector supply tank to keep the chemicals in solution. Many chemicals will settle out if not agitated.
Tom Scherer, (701) 231-7239
Extension Agricultural Engineer
The amount of water applied to a crop by a center pivot is controlled by the speed of the end tower. The amount of time the end tower is moving is determined by the setting of the percent timer in the pivot control panel. The new computerized control panels use electronic timers, but most panels use an electro-mechanical timer. Electro-mechanical percent timers are low cost ($25 to $50), readily available and prone to mechanical wear. A percent timer that causes the end tower running time to fluctuate can cause over or under application of irrigation water. Good irrigation management requires an accurate estimate of the application amount of each irrigation. It is especially important during the fruiting stage (grain filling, corn ear formation, potato tuber bulking, etc) of crops.
To check the accuracy of a percent timer (whether electro-mechanical or electronic), all you need is a view of the wheels on the end tower, a stop watch and the percent timer setting. For example, if you set the timer to 40%, then the end tower should move 24 seconds out of each minute (0.4 x 60 seconds). This can be checked by viewing the movement of the end tower wheels and using the stop watch. Some pivots don't move a continuous 24 seconds but move 12 seconds in each 30 second interval. Either way, the time of movement should add up to 24 seconds in each minute. Measure the movement for at least three one-minute periods. If the movement time fluctuates, change the timer. It will save you some future headaches and make your water application amounts reliable.
Tom Scherer, (701) 231-7239
Extension Agricultural Engineer
No. 155, July 1996
NDSU Extension Service, North Dakota State University of Agriculture and Applied
Science, and U.S. Department of Agriculture cooperating. Sharon D. Anderson, Director, Fargo,
North Dakota. Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914.
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